Fix null accelerator's

Fixes all except for cmap.  To be done separately.

Part of https://github.com/harfbuzz/harfbuzz/issues/1146

src/hb-ot-color-cbdt-table.hh

@@ -409,9 +409,6 @@ struct CBDT
     inline bool get_extents (hb_font_t *font, hb_codepoint_t glyph,
 			     hb_glyph_extents_t *extents) const
     {
-      if (!cblc)
-	return false;
-
       const void *base;
       const BitmapSizeTable &strike = this->cblc->choose_strike (font);
       const IndexSubtableRecord *subtable_record = strike.find_table (glyph, cblc, &base);
@@ -467,9 +464,6 @@ struct CBDT
     inline hb_blob_t* reference_png (hb_font_t      *font,
 				     hb_codepoint_t  glyph) const
     {
-      if (!cblc)
-	return hb_blob_get_empty ();
-
       const void *base;
       const BitmapSizeTable &strike = this->cblc->choose_strike (font);
       const IndexSubtableRecord *subtable_record = strike.find_table (glyph, cblc, &base);
@@ -525,8 +519,8 @@ struct CBDT
     private:
     hb_blob_t *cblc_blob;
     hb_blob_t *cbdt_blob;
-    const CBLC *cblc;
-    const CBDT *cbdt;
+    hb_nonnull_ptr_t<const CBLC> cblc;
+    hb_nonnull_ptr_t<const CBDT> cbdt;
 
     unsigned int cbdt_len;
     unsigned int upem;

src/hb-ot-color-sbix-table.hh

@@ -152,9 +152,6 @@ struct sbix
 
     inline bool has_data () const
     {
-      /* XXX Fix somehow and remove next line.
-       * https://github.com/harfbuzz/harfbuzz/issues/1146 */
-      if (!num_glyphs) return false;
       return table->has_data ();
     }
 
@@ -234,8 +231,8 @@ struct sbix
 				 hb_codepoint_t      glyph,
 				 hb_glyph_extents_t *extents) const
     {
-      /* Following code is safe to call even without data (XXX currently
-       * isn't.  See has_data()), but faster to short-circuit. */
+      /* Following code is safe to call even without data.
+       * But faster to short-circuit. */
       if (!has_data ())
         return false;
 
@@ -262,12 +259,12 @@ struct sbix
 
       hb_blob_destroy (blob);
 
-      return true;
+      return strike_ppem;
     }
 
     private:
     hb_blob_t *sbix_blob;
-    const sbix *table;
+    hb_nonnull_ptr_t<const sbix> table;
 
     unsigned int num_glyphs;
   };

src/hb-ot-color-svg-table.hh

@@ -75,12 +75,13 @@ struct SVG
 {
   static const hb_tag_t tableTag = HB_OT_TAG_SVG;
 
+  inline bool has_data (void) const { return svgDocEntries; }
+
   struct accelerator_t
   {
     inline void init (hb_face_t *face)
     {
       svg_blob = hb_sanitize_context_t().reference_table<SVG> (face);
-      svg_len = hb_blob_get_length (svg_blob);
       table = svg_blob->as<SVG> ();
     }
 
@@ -91,18 +92,14 @@ struct SVG
 
     inline hb_blob_t *reference_blob_for_glyph (hb_codepoint_t glyph_id) const
     {
-      if (unlikely (!svg_len))
-        return hb_blob_get_empty ();
       return table->get_glyph_entry (glyph_id).reference_blob (svg_blob, table->svgDocEntries);
     }
 
-    inline bool has_data () const { return svg_len; }
+    inline bool has_data () const { return table->has_data (); }
 
     private:
     hb_blob_t *svg_blob;
-    const SVG *table;
-
-    unsigned int svg_len;
+    hb_nonnull_ptr_t<const SVG> table;
   };
 
   inline const SVGDocumentIndexEntry &get_glyph_entry (hb_codepoint_t glyph_id) const

src/hb-ot-glyf-table.hh

@@ -276,7 +276,7 @@ struct glyf
       if (!get_offsets (glyph, &start_offset, &end_offset))
         return false; /* glyph not found */
 
-      return CompositeGlyphHeader::get_iterator ((const char*) this->glyf_table + start_offset,
+      return CompositeGlyphHeader::get_iterator ((const char *) this->glyf_table + start_offset,
 						 end_offset - start_offset,
 						 composite);
     }
@@ -476,8 +476,8 @@ struct glyf
     private:
     bool short_offset;
     unsigned int num_glyphs;
-    const loca *loca_table;
-    const glyf *glyf_table;
+    hb_nonnull_ptr_t<const loca> loca_table;
+    hb_nonnull_ptr_t<const glyf> glyf_table;
     hb_blob_t *loca_blob;
     hb_blob_t *glyf_blob;
     unsigned int glyf_len;

src/hb-ot-layout-gdef-table.hh

@@ -418,7 +418,7 @@ struct GDEF
     }
 
     hb_blob_t *blob;
-    const GDEF *table;
+    hb_nonnull_ptr_t<const GDEF> table;
   };
 
   inline unsigned int get_size (void) const

src/hb-ot-layout-gsubgpos.hh

@@ -2774,7 +2774,7 @@ struct GSUBGPOS
     }
 
     hb_blob_t *blob;
-    const T *table;
+    hb_nonnull_ptr_t<const T> table;
     unsigned int lookup_count;
     hb_ot_layout_lookup_accelerator_t *accels;
   };

src/hb-ot-name-table.hh

@@ -257,7 +257,7 @@ struct name
     const void *pool;
     unsigned int pool_len;
     public:
-    const name *table;
+    hb_nonnull_ptr_t<const name> table;
     hb_vector_t<hb_ot_name_entry_t> names;
   };
 

src/hb-ot-post-table.hh

@@ -254,7 +254,7 @@ struct post
     private:
     hb_blob_t *blob;
     uint32_t version;
-    const ArrayOf<HBUINT16> *glyphNameIndex;
+    hb_nonnull_ptr_t<const ArrayOf<HBUINT16>> glyphNameIndex;
     hb_vector_t<uint32_t, 1> index_to_offset;
     const uint8_t *pool;
     hb_atomic_ptr_t<uint16_t *> gids_sorted_by_name;